1. Field of the Invention
The present invention relates to a method of manufacturing a liquid crystal display apparatus and a liquid crystal dripping apparatus, and more particularly to a method of manufacturing a liquid crystal display apparatus, in which One Drop Fill method is used to feed liquid crystal to a substrate, and a liquid crystal dripping apparatus for use in the manufacturing method.
2. Description of the Prior Art
Recently, liquid crystal display apparatuses have been used for various applications, in that the display apparatuses are characterized by being thin and lightweight and also being capable of low-voltage drive, thus exhibiting low power consumption. Such widespread demands increase the variety of requests for liquid crystal display apparatuses. Of these requests, there are strong requests for improved display capabilities and lower costs.
Generally, a liquid crystal display apparatus has a basic configuration including a TFT (thin film transistor) substrate having a picture element electrode, a TFT, and the like, which are disposed thereon; an opposite substrate having an opposite electrode, a color filter, a spacer, and the like, which are disposed thereon; and liquid crystal sealed in between the TFT substrate and the opposite substrate.
Methods for injecting liquid crystal to be sealed in between the TFT substrate and the opposite substrate include vacuum injection and One Drop Fill (hereinafter referred to simply as “ODF” method). The ODF has the advantage of allowing a short processing time, and can achieve stable display capabilities and high productivity, as compared to the vacuum injection.
The description will be given below with regard to a method of using the ODF to inject liquid crystal to be sealed in between the TFT substrate and the opposite substrate. In the ODF, the following processes take place. First, the TFT substrate is cleaned, then the TFT substrate is coated with a polyimide film by printing technique, and then the polyimide film is cured to obtain an alignment layer. An alignment layer is also formed on the opposite substrate in the same manner.
Then, a sealant is selectively formed around a display area on the TFT substrate.
Then, a dispenser is controlled to dispense liquid crystal onto the TFT substrate through its nozzle, and thereby to put a drop of liquid crystal onto the TFT substrate. The dispenser is further controlled to travel a predetermined distance and thus to move to another drop-feed point, at which the dispenser again dispenses liquid crystal through its nozzle. Repetition of the above-mentioned operation yields a TFT substrate 100 having liquid crystals 101 arranged thereon in a grid pattern at predetermined spaced intervals, as shown in FIG. 1.
In a vacuum atmosphere, the TFT substrate and the opposite substrate are then bonded together in alignment with each other by the sealant. Thus, the liquid crystals put on the TFT substrate spread through a space enclosed with the TFT substrate, the opposite substrate, and the sealant. Incidentally, the spacer disposed on the opposite substrate maintains a given gap between the TFT substrate and the opposite substrate. The liquid crystals are sealed in between the TFT substrate and the opposite substrate in the manner as above described.
The method of using the ODF to inject liquid crystal, as mentioned above, is disclosed in Japanese Unexamined Patent Application Publication No. Hei 05 (1993)-232481, for example.
However, a problem may arise in a liquid crystal display apparatus filled with liquid crystal by using the ODF as mentioned above. Specifically, when the driving of the display allows a display image to appear, unevenness in brightness (i.e. light and shade) may develop in a grid pattern in a region in which the liquid crystals collide with each other when the liquid crystals are horizontally diffused between the substrates.